The goal of this project is to increase our knowledge regarding the nature of performance-based deficits for a group of children identified as Specifically Language Impaired or SLI. Studies have suggested that for at least a subgroup of this population, productions deficits appear to be correlated with comprehension deficits. Both competence and performance models have been employed to examine the nature of these deficits but it is unclear at this time the extent to which SLI is a performance deficit involving breakdowns in the real-time process of language. Psycholinguists recently have begun to employ on-line experimental techniques to investigate normal speakers' language performance as it relates to both comprehension and production. These experimentally controlled tasks have been successful in the study of individual's real-time simultaneous processing and integration of verbal information across different linguistic domains. These tasks have been used extensively with adults, and have recently been used with children, and adults with language impairments. The goal for this project therefore is to employ on-line experimental techniques: 1) to characterize the performance deficits in SLI, 2) to investigate the relationship between the comprehension and production deficits and, 3) to determine at what level the processing skills are impaired (e.g., lexical, sentence, or discourse). Digitized speech samples will be presented to male and female SLI children, chronologically age-matched, and language-matched normal controls. the subjects will be asked to press a button to indicate good or bad sentences. The stimuli will contain a range of lexical, morphological and syntactic errors to enable the assessment of real-time language processing. In addition, spontaneous language samples will be collected within adult-child freeplay interactions. The results of on-line performance will be compared to spontaneous speech productions to determine the degree of language processing impairment with increased processing demands.